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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+"""
+This takes a crashing qtest trace and tries to remove superflous operations
+"""
+
+import sys
+import os
+import subprocess
+import time
+import struct
+
+QEMU_ARGS = None
+QEMU_PATH = None
+TIMEOUT = 5
+CRASH_TOKEN = None
+
+write_suffix_lookup = {"b": (1, "B"),
+ "w": (2, "H"),
+ "l": (4, "L"),
+ "q": (8, "Q")}
+
+def usage():
+ sys.exit("""\
+Usage: QEMU_PATH="/path/to/qemu" QEMU_ARGS="args" {} input_trace output_trace
+By default, will try to use the second-to-last line in the output to identify
+whether the crash occred. Optionally, manually set a string that idenitifes the
+crash by setting CRASH_TOKEN=
+""".format((sys.argv[0])))
+
+def check_if_trace_crashes(trace, path):
+ global CRASH_TOKEN
+ with open(path, "w") as tracefile:
+ tracefile.write("".join(trace))
+
+ rc = subprocess.Popen("timeout -s 9 {timeout}s {qemu_path} {qemu_args} 2>&1\
+ < {trace_path}".format(timeout=TIMEOUT,
+ qemu_path=QEMU_PATH,
+ qemu_args=QEMU_ARGS,
+ trace_path=path),
+ shell=True,
+ stdin=subprocess.PIPE,
+ stdout=subprocess.PIPE)
+ stdo = rc.communicate()[0]
+ output = stdo.decode('unicode_escape')
+ if rc.returncode == 137: # Timed Out
+ return False
+ if len(output.splitlines()) < 2:
+ return False
+
+ if CRASH_TOKEN is None:
+ CRASH_TOKEN = output.splitlines()[-2]
+
+ return CRASH_TOKEN in output
+
+
+def minimize_trace(inpath, outpath):
+ global TIMEOUT
+ with open(inpath) as f:
+ trace = f.readlines()
+ start = time.time()
+ if not check_if_trace_crashes(trace, outpath):
+ sys.exit("The input qtest trace didn't cause a crash...")
+ end = time.time()
+ print("Crashed in {} seconds".format(end-start))
+ TIMEOUT = (end-start)*5
+ print("Setting the timeout for {} seconds".format(TIMEOUT))
+ print("Identifying Crashes by this string: {}".format(CRASH_TOKEN))
+
+ i = 0
+ newtrace = trace[:]
+ # For each line
+ while i < len(newtrace):
+ # 1.) Try to remove it completely and reproduce the crash. If it works,
+ # we're done.
+ prior = newtrace[i]
+ print("Trying to remove {}".format(newtrace[i]))
+ # Try to remove the line completely
+ newtrace[i] = ""
+ if check_if_trace_crashes(newtrace, outpath):
+ i += 1
+ continue
+ newtrace[i] = prior
+
+ # 2.) Try to replace write{bwlq} commands with a write addr, len
+ # command. Since this can require swapping endianness, try both LE and
+ # BE options. We do this, so we can "trim" the writes in (3)
+ if (newtrace[i].startswith("write") and not
+ newtrace[i].startswith("write ")):
+ suffix = newtrace[i].split()[0][-1]
+ assert(suffix in write_suffix_lookup)
+ addr = int(newtrace[i].split()[1], 16)
+ value = int(newtrace[i].split()[2], 16)
+ for endianness in ['<', '>']:
+ data = struct.pack("{end}{size}".format(end=endianness,
+ size=write_suffix_lookup[suffix][1]),
+ value)
+ newtrace[i] = "write {addr} {size} 0x{data}\n".format(
+ addr=hex(addr),
+ size=hex(write_suffix_lookup[suffix][0]),
+ data=data.hex())
+ if(check_if_trace_crashes(newtrace, outpath)):
+ break
+ else:
+ newtrace[i] = prior
+
+ # 3.) If it is a qtest write command: write addr len data, try to split
+ # it into two separate write commands. If splitting the write down the
+ # middle does not work, try to move the pivot "left" and retry, until
+ # there is no space left. The idea is to prune unneccessary bytes from
+ # long writes, while accommodating arbitrary MemoryRegion access sizes
+ # and alignments.
+ if newtrace[i].startswith("write "):
+ addr = int(newtrace[i].split()[1], 16)
+ length = int(newtrace[i].split()[2], 16)
+ data = newtrace[i].split()[3][2:]
+ if length > 1:
+ leftlength = int(length/2)
+ rightlength = length - leftlength
+ newtrace.insert(i+1, "")
+ while leftlength > 0:
+ newtrace[i] = "write {} {} 0x{}\n".format(
+ hex(addr),
+ hex(leftlength),
+ data[:leftlength*2])
+ newtrace[i+1] = "write {} {} 0x{}\n".format(
+ hex(addr+leftlength),
+ hex(rightlength),
+ data[leftlength*2:])
+ if check_if_trace_crashes(newtrace, outpath):
+ break
+ else:
+ leftlength -= 1
+ rightlength += 1
+ if check_if_trace_crashes(newtrace, outpath):
+ i -= 1
+ else:
+ newtrace[i] = prior
+ del newtrace[i+1]
+ i += 1
+ check_if_trace_crashes(newtrace, outpath)
+
+
+if __name__ == '__main__':
+ if len(sys.argv) < 3:
+ usage()
+
+ QEMU_PATH = os.getenv("QEMU_PATH")
+ QEMU_ARGS = os.getenv("QEMU_ARGS")
+ if QEMU_PATH is None or QEMU_ARGS is None:
+ usage()
+ # if "accel" not in QEMU_ARGS:
+ # QEMU_ARGS += " -accel qtest"
+ CRASH_TOKEN = os.getenv("CRASH_TOKEN")
+ QEMU_ARGS += " -qtest stdio -monitor none -serial none "
+ minimize_trace(sys.argv[1], sys.argv[2])